The Brain That Changes Itself by Norman Doidge

(1) From: The Brain that Changes Itself, Chapter 3

by Norman Doidge

New York: Viking, 2007. p. 59-88

The competitive nature of plasticity affects us all. There is an endless war of nerves going on inside each of our brains. If we stop exercising our mental skills, we do not just forget them: the brain map space for those skills is turned over to the skills we practice instead. If you ever ask yourself, “How often must I practice French, or guitar, or math to keep on top of it?” you are asking a question about competitive plasticity. You are asking how frequently you must practice one activity to make sure its brain map space is not lost to another.

(2) Competitive plasticity in adults even explains some of our limitations. Think of the difficulty most adults have in learning a second language. The conventional view now is that the difficulty arises because the critical period for language learning has ended, leaving us with a brain too rigid to change its structure on a large scale. (3) But the discovery of competitive plasticity suggests there is more to it. As we age, the more we use our native language, the more it comes to dominate our linguistic map space. Thus it is also because our brain is plastic—and because plasticity is competitive—that it is so hard to learn a new language and end the tyranny of the mother tongue.

(4) But why, if this is true, is it easier to learn a second language when we are young? Is there not competition then too? Not really. If two languages are learned at the same time, during the critical period, both get a foothold. Brain scans, says [Dr. Michael M.] Merzenich, show that in a bilingual child all the sounds of its two languages share a single large map, a library of sounds from both languages.

(5) Competitive plasticity also explains why our bad habits are so difficult to break or “unlearn.” Most of us think of the brain as a container and learning as putting something in it. When we try to break a bad habit, we think the solution is to put something new into the container. (6) But when we learn a bad habit, it takes over a brain map, and each time we repeat it, it claims more control of that map and prevents the use of that space for “good” habits. That is why “unlearning” is often a lot harder than learning, and why early childhood education is so important—it’s best to get it right early, before the “bad habit” gets a competitive advantage.

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(7) He laughs when he says it. “Let me tell you what happened when I began to declare that the brain was plastic. I received hostile treatment. I don’t know how else to put it. I got people saying things in reviews such as, ‘This would be really interesting if it could possibly be true, but it could not be.’ It was as if I just made it up.”

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(8) It seemed reasonable to assume that if totally new maps were forming, then new connections must have been forming among neurons. To help understand this process, Merzenich invoked the ideas of Donald O. Hebb, a Canadian behavioral psychologist who had worked with Penfield. In 1949 Hebb proposed that learning linked neurons in new ways. (9) He proposed that when two neurons fire at the same time repeatedly (or when one fires, causing another to fire), chemical changes occur in both, so that the two tend to connect more strongly. Hebb’s concept—actually proposed by Freud sixty years before—was neatly summarized by neuroscientist Carla Shatz: Neurons that fire together wire together.

(10) Hebb’s theory thus argued that neuronal structure can be altered by experience. Following Hebb, Merzenich’s new theory was that neurons in brain maps develop strong connections to one another when they are activated at the same moment in time. And if maps could change, thought Merzenich, then there was reason to hope that people born with problems in brain map–processing areas—people with learning problems, psychological problems, strokes, or brain injuries—might be able to form new maps if he could help them form new neuronal connections, by getting their healthy neurons to fire together and wire together.

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(11) When a child learns to play piano scales for the first time, he tends to use his whole upper body—wrist, arm, shoulder—to play each note. Even the facial muscles tighten into a grimace. With practice the budding pianist stops using irrelevant muscles and soon uses only the correct finger to play the note. He develops a “lighter touch,” and if he becomes skillful, he develops “grace” and relaxes when he plays. (12) This is because the child goes from using a massive number of neurons to an appropriate few, well matched to the task. This more efficient use of neurons occurs whenever we become proficient at a skill, and it explains why we don’t quickly run out of map space as we practice or add skills to our repertoire.

(13) Merzenich and Jenkins also found that as neurons are trained and become more efficient, they can process faster. This means that the speed at which we think is itself plastic. Speed of thought is essential to our survival. Events often happen quickly, and if the brain is slow, it can miss important information. In one experiment Merzenich and Jenkins successfully trained monkeys to distinguish sounds in shorter and shorter spans of time. (14) The trained neurons fired more quickly in response to the sounds, processed them in a shorter time, and needed less time to “rest” between firings. Faster neurons ultimately lead to faster thought—no minor matter—because speed of thought is a crucial component of intelligence. IQ tests, like life, measure not only whether you can get the right answer but how long it takes you to get it.

(15) They also discovered that as they trained an animal at a skill, not only did its neurons fire faster, but because they were faster their signals were clearer. Faster neurons were more likely to fire in sync with each other—becoming better team players—wiring together more and forming groups of neurons that gave off clearer and more powerful signals. This is a crucial point, because a powerful signal has greater impact on the brain. When we want to remember something we have heard we must hear it clearly, because a memory can be only as clear as its original signal.

(16) Finally, Merzenich discovered that paying close attention is essential to long-term plastic change. In numerous experiments he found that lasting changes occurred only when his monkeys paid close attention. When the animals performed tasks automatically, without paying attention, they changed their brain maps, but the changes did not last. We often praise “the ability to multitask.” While you can learn when you divide your attention, divided attention doesn’t lead to abiding change in your brain maps.

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(17) Merzenich now became aware of the work of Paula Tallal at Rutgers, who had begun to analyze why children have trouble learning to read. Somewhere between 5 and 10 percent of preschool children have a language disability that makes it difficult for them to read, write, or even follow instructions. Sometimes these children are called dyslexic.

(18) Babies begin talking by practicing consonant-vowel combinations, cooing “da, da, da” and “ba, ba, ba.” In many languages their first words consist of such combinations. In English their first words are often “mama” and “dada,” “pee pee,” and so on. Tallal’s research showed that children with language disabilities have auditory processing problems with common consonant-vowel combinations that are spoken quickly and are called “the fast parts of speech.” The children have trouble hearing them accurately and, as a result, reproducing them accurately.

(19) Merzenich believed that these children’s auditory cortex neurons were firing too slowly, so they couldn’t distinguish between two very similar sounds or be certain, if two sounds occurred close together, which was first and which was second. Often they didn’t hear the beginnings of syllables or the sound changes within syllables. (20) Normally neurons, after they have processed a sound, are ready to fire again after about a 30-millisecond rest. Eighty percent of language-impaired children took at least three times that long, so that they lost large amounts of language information. When their neuron-firing patterns were examined, the signals weren’t clear.

(21) “They were muddy in, muddy out,” says Merzenich. Improper hearing led to weaknesses in all the language tasks, so they were weak in vocabulary, comprehension, speech, reading, and writing. Because they spent so much energy decoding words, they tended to use shorter sentences and failed to exercise their memory for longer sentences. Their language processing was more childlike, or “delayed,” and they still needed practice distinguishing “da, da, da” and “ba, ba, ba.”

(22) When Tallal originally discovered their problems, she feared that “these kids were ‘broken’ and there was nothing you could do” to fix their basic brain defect. But that was before she and Merzenich combined forces.

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(23) Fast ForWord is the name of the training program they developed for language-impaired and learning-disabled children. The program exercises every basic brain function involved in language from decoding sounds up to comprehension—a kind of cerebral cross-training.

(24) The program offers seven brain exercises. One teaches the children to improve their ability to distinguish short sounds from long. A cow flies across the computer screen, making a series of mooing sounds. The child has to catch the cow with the computer cursor and hold it by depressing the mouse button. Then suddenly the length of the moo sound changes subtly. At this point the child must release the cow and let it fly away. A child who releases it just after the sound changes scores points. (25) In another game children learn to identify easily confused consonant-vowel combinations, such as “ba” and “da,” first at slower speeds than they occur in normal language, and then at increasingly faster speeds. Another game teaches the children to hear faster and faster frequency glides (sounds like “whooooop” that sweep up). (26) Another teaches them to remember and match sounds. The “fast parts of speech” are used throughout the exercises but have been slowed down with the help of computers, so the language-disabled children can hear them and develop clear maps for them; then gradually, over the course of the exercises, they are sped up. Whenever a goal is achieved, something funny happens: the character in the animation eats the answer, gets indigestion, gets a funny look on its face, or makes some slapstick move that is unexpected enough to keep the child attentive. (27) This “reward” is a crucial feature of the program, because each time the child is rewarded, his brain secretes such neurotransmitters as dopamine and acetylcholine, which help consolidate the map changes he has just made. (Dopamine reinforces the reward, and acetylcholine helps the brain “tune in” and sharpen memories.)

(28) Children with milder difficulties typically work at Fast ForWord for an hour and forty minutes a day, five days a week for several weeks, and those with more severe difficulties work for eight to twelve weeks.

(29) The first study results, reported in the journal Science in January 1996, were remarkable. Children with language impairments were divided into two groups, one that did Fast ForWord and a control group that did a computer game that was similar but didn’t train temporal processing or use modified speech. The two groups were matched for age, IQ, and language-processing skills. (30) The children who did Fast ForWord made significant progress on standard speech, language, and auditory-processing tests, ended up with normal or better-than-normal language scores, and kept their gains when retested six weeks after training. They improved far more than children in the control group.

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(31) Willy Arbor is a seven-year-old from West Virginia. He’s got red hair and freckles, belongs to Cub Scouts, likes going to the mall, and, though barely over four feet tall, loves wrestling. He’s just gone through Fast ForWord and has been transformed.

(32) “Willy’s main problem was hearing the speech of others clearly,” his mother explains. “I might say the word ‘copy,’ and he would think I said ‘coffee.’ If there was any background noise, it was especially hard for him to hear. Kindergarten was depressing. You could see his insecurity. (33) He got into nervous habits like chewing on his clothes, or his sleeve, because everybody else was getting the answer right, and he wasn’t. The teacher had actually talked about holding him back in first grade.” Willy had trouble reading, both to himself and aloud.

(34) “Willy,” his mother continues, “couldn’t hear change in pitch properly. So he couldn’t tell when a person was making an exclamation or just a general statement, and he didn’t grasp inflections in speech, which made it hard for him to read people’s emotions. Without the high and low pitch he wasn’t hearing that wow when people are excited. It was like everything was the same.”

(35) Willy was taken to a hearing specialist, who diagnosed his “hearing problem” as caused by an auditory-processing disorder that originated in his brain. He had difficulty remembering strings of words because his auditory system was so easily overloaded. “If you gave him more than three instructions, such as ‘please put your shoes upstairs—put them in the closet—then come down for dinner,’ he’d forget them. (36) He’d take his shoes off, go up the steps, and ask ‘Mom what did you want me to do?’ Teachers had to repeat instructions all the time.” Though he appeared to be a gifted child—he was good at math—his problems held him back in that area too.

His mother protested making Willy repeat first grade and over the summer sent him to Fast ForWord for eight weeks.

(37) “Before he did Fast ForWord,” his mother recalls, “you’d put him at the computer, and he got very stressed out. With this program, though, he spent a hundred minutes a day for a solid eight weeks at the computer. He loved doing it and loved the scoring system because he could see himself going up, up, up,” says his mother. As he improved, he became able to perceive inflections in speech, got better at reading the emotions of others, and became a less anxious child. (38) “So much changed for him. When he brought his midterms home, he said, ‘It is better than last year, Mommy.’ He began bringing home A and B marks on his papers most of the time—a noticeable difference...Now it’s ‘I can do this. This is my grade. I can make it better.’ I feel like I had my prayer answered, it’s done so much for him. It’s amazing.” A year later he continues to improve.

(39) Merzenich’s team started hearing that Fast ForWord was having a number of spillover effects. Children’s handwriting improved. Parents reported that many of the students were starting to show sustained attention and focus. Merzenich thought these surprising benefits were occurring because Fast ForWord led to some general improvements in mental processing.

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(40) A number of children who took standardized tests shortly after completing Fast ForWord showed improvements not only in language, speaking, and reading, but in math, science, and social studies as well. Perhaps these children were hearing what was going on in class better or were better able to read—but Merzenich thought it might be more complicated.

(41) “You know,” he says, “IQ goes up. We used the matrix test, which is a visual-based measurement of IQ—and IQ goes up.”

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What is remarkable about the cortex in the critical period is that it is so plastic that its structure can be changed just by exposing it to new stimuli. That sensitivity allows babies and very young children in the critical period of language development to pick up new sounds and words effortlessly, simply by hearing their parents speak; mere exposure causes their brain maps to wire in the changes. (42) After the critical period older children and adults can, of course, learn languages, but they really have to work to pay attention. For Merzenich, the difference between critical-period plasticity and adult plasticity is that in the critical period the brain maps can be changed just by being exposed to the world because “the learning machinery is continuously on.”

(43) It makes good biological sense for this “machinery” always to be on because babies can’t possibly know what will be important in life, so they pay attention to everything. Only a brain that is already somewhat organized can sort out what is worth paying attention to.

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(44) What if it were possible to reopen critical-period plasticity, so that adults could pick up languages the way children do, just by being exposed to them? Merzenich had already shown that plasticity extends into adulthood, and that with work—by paying close attention—we can rewire our brains. But now he was asking, could the critical period of effortless learning be extended?